The problem is it wouldn’t have a SOO feel about it.
The sport has next to no following in those nations.
You’re not going to go in to work and brag to Paddy or jock that England beat them as he wouldn’t care. Even in the north it’s a minority sport, it would be nothing like origin.
Not only that but the teams are populated with English players who for the most part have little or no cultural links to those nations. I would qualify for Scotland and I don’t cut about in a kilt and honestly I don’t know many English people with heritage from other home nations that really embrace their cultures. It’s not the same as the pacific teams down here.
I know the only way it is going to grow is by plying games but it’s not as simple as people think.
Time for England to actually do something and try grow the game in their neighbouring countries, as they should have been for the last 100 years.
Nothing ever changes if you just keep saying why things can't be done.
Whether its combined Celtic, or just Wales or Ireland or Scotland, you're right that fans buying into it would be limited. At least for a while. Maybe even a long while.
But the players would. Guys like Regan Grace who should have been selected for GB but was clearly brushed because he's not in the England setup.
It might take some time, but fans will buy into a competitive game, where the players give a shit, and is marketed well.